Method and device for carrying out work on an object which is present under water

ABSTRACT

A method for carrying out work on an object which is present under water, in particular, a shipwreck, wherein persons make their way to the object under water and carry out the work in artificial light. A cover is provided over the object, which cover in the main abuts the bottom on which or in which the object is present in surrounding relationship with respect to the object. The cover encloses a space in which persons can work and it comprises an entrance for admitting persons to the space.

The invention relates to a method and a device for carrying out work oran object which is present under water, wherein persons make their wayto said object under water and carry out said work in artificial light.Such a method can be used in particular when carrying out work on ashipwreck, but the method can also be used for carrying out other kindsof work under water, for example in a river or on the seabed. In thisconnection, the removal of undesirable objects, such as poison gasgrenades present in the seabed may be considered.

When work is being carried out under water, visibility is often limitedbecause the water contains solid particles, which are carried along bycurrents in the water. Another problem that occurs when carrying outwork under water is the fact that there is often a current in the water.Thus, there is a continuous current in rivers, and work on the seabed isoften impeded by a changing current caused by the tides.

When there is a current in the water, limited visibility ensues, toolsand other objects may be carried along by the current, holes that havebeen dug in the bottom may fill up and, especially when the current is achanging current, the people who carry out the work may becomedisoriented. In the case of tidal currents, it is often possible tocarry out work under water only during the short period of time duringwhich there is no current.

The object of the invention is to provide a method and a device whichmake it possible to carry out work under water in an efficient manner.

In order to accomplish that objective, a cover is provided over theobject, which cover in the main abuts the bottom on which or in whichthe object is present in surrounding relationship with respect to saidobject, which cover encloses a space in which persons can work andwithin which artificial lighting is provided, which cover comprises anentrance for admitting persons to said space. Thus, a space is providedround the object in which there is no current and in which an optimumenvironment can be created for carrying out work.

Preferably, clean water is supplied to said space, which can take placenear the highest point of said space, which water is preferablyfiltrated. To that end, filters may be provided on the upper side of thecover, through which filters the water is passed. Outside the cover, thewater is clearer near the upper side of the cover than near the bottom,so that this is a suitable place for drawing in water from thesurrounding space.

In another preferred embodiment, water is supplied to said space byutilizing the flow of the water surrounding the cover. One side wall isthereby provided with a water inlet, whilst one side on the other sideof the cover is provided with a water inlet. Only cleaned water can flowinto the space through a filter mounted in said inlet. When there arechanging currents, it is possible to use several inlets and outlets,which can alternately be opened and closed.

In one preferred embodiment, means are present for draining water fromthe space. Said means preferably comprise drain openings in the sidewall of the cover, namely at a height of less than half, preferably lessthan one-quarter, more preferably less than one-eighth, of the height ofthe space under the cover. As a result, the water in the lower part ofthe space, which the level of pollution is usually highest, will bedrained off, whilst clean water can be supplied on the upper side of thecover.

Preferably, the device is provided with a fixedly disposed pump, whichis connected, via a flexible conduit, to a nozzle by means of whichsubstance can be sucked from the space. In this manner the personscarrying out work can remove polluted water or sand at random places.

Preferably, a number of connecting points are present on the inside ofthe cover for connecting the flexible conduit thereto, in whichconnecting points said flexible conduit can be connected to the fixedlydisposed pump.

Preferably, the cover is provided with a downwardly extending wall atits circumferential edge, which wall can be pressed into the bottom.When a layer of sand is present on the bottom, this is a very efficientmanner of effecting a proper connection to the bottom.

Preferably, the cover is provided with suction anchors, by means ofwhich the cover is pressed against the bottom. Such suction anchors areknown per se and they are capable of pressing the edge of the coveragainst or into the bottom.

It is also possible to press the cover against the bottom by reducingthe pressure under said cover in comparison with the pressure outsidethe cover. Naturally, this is only possible when the edge of the coverin the main abuts the bottom and when direct and indirect connectionsbetween the interior and the exterior of the cover, inter aliaconnections which take place via filters, are closed. When the pressureis reduced in this manner, the edge of the cover can be pressed down toextend into the bottom.

Preferably, a piece of a flexible material is secured to the edge of thecover which extends to a point near the bottom, which material can beprovided between said edge and the bottom. The flexible material maycomprise one or more compartments, which can be filled with a materialhaving a higher specific mass than water, for example sand and/orgravel. In this manner it is possible to obtain a good connection to thebottom, in particular when the bottom is not flat and consists ofstones, for example.

Preferably, means are present for limiting the pressure differencebetween the space under the cover and the surrounding space. Such asafety valve is capable of limiting the pressure difference in twodirections, for example at a level of less than one per cent.

By keeping the pressure in said space slightly higher than that in thesurrounding space, it is possible to prevent an undesirably large amountof water flowing into said space from the surrounding space, for examplewhen opening a lock.

Preferably, a living space is present under or near said cover, whichspace is capable of accommodating persons. Air can be supplied to saidliving space, and the living space may be heated, whereby persons whocarry out work can stay in said space from time to time. This isimportant in particular if work is being carried out at great depth, sothat persons must follow a lengthy procedure in order to get to thewater surface. In that case, they may even carry out work for severaldays on end without having to make their way to the water surface fromtime to time.

Preferably, the cover can be moved in floating position, whereinfloating bodies are present near the circumferential edge (seen in planview), which floating bodies are filled with air. It is possible therebyto move the cover even in very shallow water. In order to ensure thatthe cover will remain stable while being moved, the cover can be turnedupside-down, that's, floating in upside-down position, in which positionthe cover can be towed by a tugboat.

Preferably, the cover is moved up from the bottom by fillingcompartments which are present near the centrally positioned upper partof the cover with air. Said compartments are provided with pressurerelief valves in order to allow air to escape from the compartmentswhile the cover is rising, so that the air pressure in the compartmentscan decrease. This makes it possible for the cover to rise in the waterin a stable position.

Preferably, an engine room is present in or near the cover, in which aircan be compressed and/or electricity can be generated. It is alsopossible, however, to carry out such operations in a module which floatson the water surface, which module is connected to said space by meansof the necessary hoses and conducting wires.

In order to obtain proper lighting of the space, lighting equipment isprovided in the side walls of the cover, which lighting equipmentconsists of lamps which are mounted at a height of less thanthree-quarters, preferably less than half, of the height of said space.Since the persons who carry out the work are often positioned above theplace where they are carrying out said work, illumination from the sideis advantageous.

The outside of the cover, seen in sectional view of the cover, ispreferably semi-circular, ellipsoid or oval, or shaped otherwise with aview to minimizing the flow resistance of the cover.

Further aspects of the invention and of the method, which can be usedseparately as well as in combination with each other, will be describedby means of an embodiment and be defined in the claims.

Preferably, the inner side of the cover is provided, at least locallyso, with light-reflecting means. This will enhance visibility within thecover. Said reflection can also be achieved by lining the cover with alightly coloured, preferably practically white, material.

In order to explain the invention more fully, an embodiment of a coverwill now be described with respect to the drawing.

FIG. 1 shows a cover disposed on the seabed;

FIG. 2 is a longitudinal sectional view of cover;

FIG. 3 is an entry lock;

FIG. 4 is a filter device;

FIG. 5 is a ring line;

FIG. 6 is a cross-sectional view of the cover;

FIG. 7 shows a suction anchor; and

FIGS. 8-10 show the cover being turned upside-down.

The figures are merely schematic representations, wherein partscorresponding to each other are indicated by the same numerals.

FIG. 1 shows a cover 1, which is secured to a bottom 2 under water. Thecover comprises a wall 3 of sheet steel, which is shown in cut-away viewin three places in FIG. 1. The sheets of wall 3 are mounted on girders4, thus providing a solid structure having a length of 80 meters, awidth of 30 meters and a height of 10 meters, for example. The sheetsteel has a thickness of 4-8 mm, for example. A space 5 has been createdunder cover 1, in which space water is present, within which water ispresent whose pressure substantially corresponds to that of the wateroutside cover 1, which water in space 5 is separated from itssurroundings, however, thus making it possible to condition said water.

The cover according to the embodiment as shown in FIG. 1 is providedalong its bottom edge with a downwardly extending wall 6, which has beeninserted into bottom 2 by means of a number of suction anchors 7.Suction anchors, which are capable of sinking into a bottom and thusdeveloping a large downward force, are known per se.

Cover 1 forms an enclosure which can be positioned on the bottom of thesea or of a river, and within which the water can be conditioned, forexample to enable examination of a shipwreck. On its upper side, cover 1is provided with two filter devices 8, by means of which water from thesurrounding space can be filtered in order to be introduced into thespace within cover 1 without any Pollution being present therein. Thefilters may also be fitted in such a manner that they do not extendoutside the cover, and they may be closable so as to block thethrough-flow of water.

The cover is furthermore provided with hatches 9, which can be openedand closed by means of hydraulic cylinders 10. This makes it possible tomove goods to and from space 5 by means of a hoisting cable 11 which islowered into the water.

The cover is furthermore provided with locks 12, through which personsand/or goods can pass in order to enter space 5 or leave said space 5.

FIG. 2 is a longitudinal sectional view which shows a number of theaforesaid parts, such as the walls 6 inserted into the bottom and thesuction anchors 7. A floating body 13 surrounds the cover near the loweredge thereof. In order to make the cover float, said floating body 13,which may be subdivided into compartments, can be entirely or partiallyfilled with air.

A number of lamps 14 are mounted along the side wall of cover 1 forlighting the space 5. Said lamps can be aimed in the desired direction,so that certain parts of space 5 can be optimally lighted as desired.

In FIG. 2, a large lock 15, which is dimensioned to admit large objects,is positioned beside lock 12, which functions to admit persons. Saidlock 15 is provided with a closable opening at both ends, which openingcan alternately be opened and closed.

Lock 12 forms the entrance to a living space consisting of sleepingspace 16, a living space 17, a lock 18 and a workshop 19. Preferably,the air pressure that prevails in all of said spaces corresponds to thewater pressure outside said spaces. Moreover, said spaces are heated toa temperature which makes it possible for persons to stay therein forprolonged periods of time. A persons can make his way to space 5 and/orto the water outside the cover via lock space 18 and lock space 12.

On the upper side, said cover is provided with a floating body 20, whichconsists of compartments 21 which may be selectively filled with wateror with air. This makes it possible to change the weight of the cover,thus enabling the cover to move up or down in the water.

FIG. 3 is a more detailed view of lock 15 (FIG. 2). Lock 15 is providedwith an upper cover 22, which pivots about pivot pin 24, and with alower cover 23, which pivots about pin 25. Upper cover 22 can be openedby means of a hydraulic cylinder 26 and it can be locked by means of alatch 27, which can be operated both inside and outside the lock space.Lower cover 23 is operated by a hydraulic cylinder (not shown), and itis likewise provided with a latch 28, which can be operated both insideand outside the lock. Operating means for operating the hydrauliccylinders to open the covers 22, 23 are furthermore present both insidethe lock spaces and outside the lock spaces.

Water is sucked from the lock space by means of pump 29, and clean watercan flow to said lock space via opening 30. The supplying and drainingof water can be controlled by means of valves 31.

FIG. 4 shows a filter device 8, by means of which water which is beingdrawn into space 5 from the surrounding space is filtered. Said filterdevice is provided with a number of filter elements 32, which aredisposed in a space 33 which is in communication with the spacesurrounding cover 1. When the pressure prevailing in space 5 is lowerthan the pressure in the surrounding space, water which is present inspace 33 will be sucked into filter elements 32 and subsequently becarried to space 5 (arrow 34). In order to keep filter elements 32clean, a pressure impulse is given from time to time by supplying airvia conduit 35 (arrow 36), which air effects a flow through the filterin opposite direction, which has a cleaning effect on filter elements32. The solid particles which are retained by the filter elements 32will sink and can be drained off via conduit 37 (arrow 38).

Cover 39 of the filter device is provided with openings through whichthe water can pass, and it is secured by means of fasteners 41. Cover 39can be removed in order to exchange filter element 32.

FIG. 5 is a plan view of a ring line 42, which is provided near thecircumferential edge within the cover. Said ring line 42 has a diameterof 150-200 mm, for example, and it is provided with a large number ofsmall holes for passing, water exiting space 5 and being drained off viaring line 42 to outlet 45 (arrow 46). Said holes for draining water (notshown) have a diameter of 6 mm, for example.

Ring line 42 is provided with a number of attachment points 47, to whichwires 48, which are preferably made of steel, can be attached. Wires 48form a grid, which can be formed so as to facilitate the measuring of ashipwreck for example.

Ring line 42 is furthermore provided with a number of closable openings50, to which flexible hoses can be connected, which hoses can be usedfor draining off polluted water at random places within space 5.

Furthermore, there may be provided a similar ring line comprisingconnections to which flexible hoses can be connected for sucking offsand and the like at random places within space 5.

FIG. 6 shows a sectional view of a part of the cover at the location oflock 12, lock 61 and lock 59, which sectional view extendsperpendicularly to the sectional view of FIG. 2. The shape of entrance53 to lock 12, seen in plan view, is indicated at 51. Numeral 43indicates the entrance door to lock 12, which lock 12 is connected tolock space 18 via door 62. A lock 61 connects lock space 18 to space 5within cover 1, which lock 61 comprises a hatch 52 on its lower side anda door 63 which provides the connection to lock space 18.

Persons can move from space 6 to lock 61 via cover 52, and from outsidethe cover to lock 12 via cover 43. Naturally, persons can leave lockspace 18 to space 5 or to the water outside cover 1 in a similar manner.

FIG. 6 furthermore shows another lock 59, through which persons can gofrom space 5 to the space surrounding cover 5, and vice versa. Forsafety reasons it is desirable that enough locks which can be usedindependently of each other be present.

FIG. 7 schematically shows the operation of a suction anchor 7, whichcan sink into bottom 2, as is shown in FIG. 7 by drawing bottom 2 twice.Suction anchor 7 sinks into the bottom in that water can be removed fromthe interior of the suction anchor by means of conduits 54 (arrows 55).Attached to said suction anchor is wall 6, which can be inserted intothe bottom, at least partially so, by means of suction anchor 7.

Cover 1 can be moved by pulling it through the water in floatingposition. When cover 1 is to be moved through shallow water, floatingbodies 13 can be filled with air, and additional floating bodies can beattached to the edge of the cover, if necessary.

When cover 1 is to be moved a large distance, it may be desirable togive the cover a more stable position, to which end the cover may beturned upside down. Said turning upside down is shown in FIGS. 8-10.

FIG. 8 shows the situation wherein the compartments of floating bodies20 are filled with air, causing cover 1 to float near the water surface56. Floating body 13 is then filled with air on one side (FIG. 9), as aresult of which cover 1 will tilt. Cover 1 can be kept in this positionby means of a cable 57 when the other side of floating body 13 is filledwith air (FIG. 10) as well. In the meantime, floating body 20 can befilled with water again, at least partially so, and that in such amanner that cover 1 starts to tilt (arrow 58), as a result of whichcover 1 is positioned upside down in the water. When subsequently thewater present within the cover is pump out, a situation is providedwherein the cover lies in the. water just as stable as a boat.

In, order to have the cover abut the bottom properly rather than beinserted therein, the edge may be provided with a flexible, tubularbody, for example having a diameter of 1-3 meters, which body can befilled with sand and gravel so as to abut the bottom. Preferably, such atubular body is subdivided into compartments.

The above-described embodiment is merely given by way of example, manyvariations are possible.

What is claimed is:
 1. A method for carrying out work on an object whichis present under water, in particular a shipwreck, wherein persons maketheir way to said object under water and carry out said work inartificial light, characterized in that cover is provided over theobject, which cover abuts the bottom on which or in which the object ispresent in surrounding relationship with respect to said object, whichcover encloses a space in which persons can work and within whichartificial lighting is provided, which cover comprises an entrance foradmitting persons to said space, and characterized in that a downwardlyextending wall is pressed into the bottom at the circumferential edge ofsaid cover.
 2. A method according to claim 1, characterized in thatclean water is supplied to said space, preferably near the highest pointof said space.
 3. A method according to claim 2, characterized in thatthe water being supplied is filtrated.
 4. A method according to claim 1,characterized in that water is supplied to said space by utilizing theflow of the water surrounding the cover.
 5. A method according to claim1, characterized in that water is drained from said space.
 6. A methodaccording to claim 5, characterized in that water is drained from saidspace near the circumferential edge at a height of less than half,preferably less than one-quarter, more preferably less than one-eighth,of the height of said space.
 7. A method according to claim 5,characterized in that substance is sucked from said space via a flexibleconduit, which is connected to a fixedly disposed pump.
 8. A methodaccording to claim 7, characterized in that a number of connectingpoints are present on the inside of the cover for connecting theflexible conduit thereto, in which connecting points said flexibleconduit can be connected to a fixedly disposed drainage system.
 9. Amethod according to claim 1, characterized in that a wire is stretchedat least between two points near the circumferential edge of the coverso as to be able to determine a position.
 10. A method according toclaim 1, characterized in that said cover is pressed against the bottomby means of suction anchors.
 11. A method according to claim 1,characterized in that the cover is pressed against the bottom byreducing the pressure under said cover in comparison with the pressureoutside the cover.
 12. A method according to claim 1, characterized inthat the pressure difference between the space under the cover and thesurrounding space is maintained at a level of less than one per cent.13. A method according to claim 1, characterized in that the pressureunder the cover is essentially maintained at a level higher than thatoutside the cover.
 14. A method according to claim 1, characterized inthat persons carrying out work under the cover can go to a living spacefrom time to time, which living space is at least partially filled withair, with the pressure of said air being substantially the same as thehydrostatic pressure prevailing under the cover, the temperature in saidliving space preferably being room temperature.
 15. A method accordingto claim 1, characterized in that the cover is moved in floatingposition, wherein floating bodies filled with air are present near thecircumferential edge.
 16. A method according to claim 1, characterizedin that air is compressed or electricity is generated in an engine roomwhich is present in or near said cover.
 17. A method according to claim1, characterized in that a module which floats in the watersubstantially above said cover, in which module air compressors orelectricity generators are present, which are connected to said space bymeans of, respectively, hoses and conducting wires.
 18. A methodaccording to claim 1, characterized in that lamps are mounted on theinside of the cover at a height of less than three-quarters, preferablyless than half, of the height of said space.
 19. A method according toclaim 1, characterized in that said cover is moved while floating on thewater, wherein said cover floats on the water in an upside-downposition.
 20. A device for carrying out work on an object which ispresent under water, in particular a shipwreck, wherein persons maketheir way to said object under water and carry out said work inartificial light, characterized by a cover to be provided over theobject, which cover is capable of essentially abutting the bottom onwhich or in which the object is present in surrounding relationship withrespect to said object, which cover encloses a space in which personscan work and within which artificial lighting is provided, which covercomprises an entrance for admitting persons to said space, andcharacterized in that said cover is provided near its circumferentialedge with a downwardly extending wall, which can be pressed into thebottom.
 21. A device according to claim 20, characterized by means forsupplying clean water to said space, preferably near the highest pointof said space.
 22. A device according to claim 21, characterized in thata water inlet is present in one side wall and that a water inlet ispresent in a side wall on the other side of the cover.
 23. A deviceaccording to claim 20, characterized in that filters are present forfiltering the water being supplied to said space.
 24. A device accordingto claim 20, characterized by means for draining water from said space.25. A device according to claim 24, characterized in that drain openingsare present in said space under said cover water, near thecircumferential edge, at a height of less than half, preferably lessthan one-quarter, more preferably less than one-eighth, of the height ofsaid space.
 26. A device according to claim 24, characterized in that aflexible conduit, which is connected to a fixedly disposed pump, isprovided for sucking substance from said space.
 27. A device accordingto claim 26, characterized in that a number of connecting points arepresent on the inside of the cover for connecting the flexible conduitthereto, in which connecting points said flexible conduit can beconnected to a fixedly disposed drainage system.
 28. A device accordingto any claim 20, characterized in that said cover is provided near itscircumferential edge with attachment points, to which wires can beattached, which wires can form a grid.
 29. A device according to claim20, characterized by suction anchors for pressing said cover against thebottom.
 30. A device according to claim 20, characterized by means forreducing the pressure under said cover so as to press the cover againstthe bottom, or by means for increasing said pressure so as to exert anupward force on said cover.
 31. A device according to claim 20,characterized by means for limiting the pressure difference between thespace under the cover and the surrounding space.
 32. A device accordingto claim 20, characterized by a living space present under or near saidcover, which space is capable of accommodating persons, and by means forsupplying air to said living space or by means for heating said livingspace.
 33. A device according to claim 20, characterized by floatingbodies positioned near the circumferential edge, which floating bodiescan be filled with air.
 34. A device according to claim 20,characterized in that an engine room is provided in or near said cover,in which air can be compressed or electricity can be generated.
 35. Adevice according to claim 20, characterized, by a module which can floatin the water above said cover, in which module air compressors orelectricity generators are present, which can be connected to said spaceby means of, respectively, hoses and conducting wires.
 36. A deviceaccording to claim 20, characterized by compartments present near thecentrally positioned upper part of said cover, into which air can beintroduced so as to cause the cover to rise in the water.
 37. A deviceaccording to claim 20, characterized in that lamps are mounted on theinside of the cover at a height of less than three-quarters, preferablyless than half, of the height of said space.
 38. A device according toclaim 20, characterized in that the outside of the cover, seen insectional view of the cover, is essentially semi-circular, ellipsoid oroval.
 39. A device according to claim 20, characterized in that theinside of the cover is at least locally provided with means whichreflect light.
 40. A device according to claim 39, characterized in thatthe inside of the cover, at least part thereof, has a light colour.